This invention relates generally to packing glands and more particularly concerns live loading packing glands.
Presently known packing glands use a primary set of packing consisting of five to six rings of packing, a lantern ring followed by a secondary set of packing consisting of five to six rings of packing and a follower to compress the packing. In some instances the follower is live loaded by springs or Beleville washers which maintain a constant pressure on the packing and create a type of constant adjustment to the packing.
There are several problems with these glands. Due to the mass and density of packing materials, a maximum of five rings of packing can be compressed. Since the present live loading glands only apply a pressure to the outer end of the secondary packing, once the gland has been packed, neither the follower nor the live loading has the ability to tighten or compress the primary packing.
Since the primary packing is not properly compressed, leakage in a valve incorporating the gland is prevented primarily by the secondary packing gland. During its initial life, the primary packing gland minimizes but does not eliminate leakage. During the continued life of the gland, as leakage continues, the seepage rate of the process into the gland increases, further damaging the primary gland and increasing the rate of seepage. This is especially true if the process employs highly corrosive catalysts which accelerate erosion of both the gland and the stem which it surrounds.
It is, therefore, an object of this invention to provide a packing gland that makes effective use of its primary packing. It is a further object of this invention to provide a packing gland in which the primary and secondary packing are both compressed under relatively uniform compression. A correlative object of this invention is to provide a packing gland which employs both internal and external gland compression.